Electrodeposition of alloys



Dec. 22, 1931. R M. BURNS ET AL ELECTRODEPOSITION OF ALLOYS Filed Sept. 8, 1926 Patented Dec. 22, 1931 vUNITED STATES PATENT; OFFICE ROBERT MQBURNS, F BROOKLYN, N EW YORK, .AND CLARENCE W. WARNER, GLEN RIDGE, NEW JERSEY, ASSIGNORS TO BELL TELEPHONE LABORATORIES, moon- PORATED, OF NEW YORK, N. Y., A CORPORATION 0FA N EW' YORK ELECTRODEPOSITION 0F .ALLOYS Application filed September 8, 1926. Serial No.v,184i,165.

This invention relates to electrochemical processes and more particularly .to the electrodeposition of alloys.

An object of this invention is to electrochemically deposit an alloy which will have a substantially uniform composition throughout.

In accordance with one embodiment of this invention there are produced smooth, flexible deposits of an alloy of uniform composition throughout, in the form of thin sheets which have suiicient strength to withstand stripping from the cathode on whi-ch they are ormed.

If, over a period of time, two metals are to be electrodeposited simultaneously in a definite proportion, it is necessary that it be equally easy for each metaltobe'fdeposited in its desired proportion. The ease zo with which ions of a metal in solution leave the solution and deposit on the cathode is measured by the potential of the cathode against the solution. If a solution contains ions of two -metals in a givenyproportion and it is desired to deposit them on a cath- 0de in thislproportion, of the cathode with respect to one of the metals in the solution must be the same as the potential of this cathode with respect to the other metal in the solution. This is commonly difficult to realize in practice. Thus, when depositing two metals-that have similar cathode potentials, such as copper and zinc, out of a cyanide solution, as it normally done in brass plating, the instantaneous cathode potential of the copper in the solution may become'diiferent from that of the zinc in the solution, resulting in a brass deposit that is either copper rich or zinc rich then the potential and correspondinglycopper colored or else conditions admit of regulation or control as does temperature, proportion of different metal ions, or presence of other substances, but it is diflicult, if not impossible, to maintain the average instantaneous."current density in the electrolyte constant. this were possible, the current density would still vary for different points on the surface ofthe cathode, depending on the distance be- 'tween the anode and various points on the cathode.

Even if` When depositing two or more metals s'i-- multaneously to obtain an alloy of the metals,

a variation in current density usually causes the cathode potential of one of the metals to change in greater or lesser degree thanduced, after which the second metal-,will de-- posit in greater amount. i ,In accordance with the present invention, for given operating'conditions, the slope and ythe axial displacement of the. current densitycathode potention curves for the metals composing an alloy are changed by varying the composition of the electrolyte until the curves for the several component metals coincide over a substantial dportion of the current density range.- variation of cathode potential with current density is the same for each metal composing the alloy, and consequently, a deposit of uniform composition is obtained over the entire surface of the cathode even with appreciable changes in current density. Moreover, the vdeposit is smooth, flexible and of sul'licient strength to withstand stripping from the cathode. In order to avoid brittleness in the deposited alloy, the acidity of the electrolyte is maintained within certain` narrow limlts. -In the following description, reference is Even where the rate of change ofA Under these conditions, thel the two metals at made one form of apparatus and one set of operating conditions which may be emobtained by employing plo ed to deposit an alloy composed of 79% nic el and 21% iron. It is to be understood, however, that the invention is not limited to this particular apparatus nor to the method of making this particular alloy.

Referring to the drawings, Fig. 1 is a diagrammatic view of the electrodepositing apparatus with the front portion of the vat removed. Figs. 2 to 4, inclusive, show current density-cathode potential curves for the deposition of iron and nickel when employing electrolytes of various compositions and indicate how the curves for the deposited metals may be moved into proximity. by changinglthe composition of the electrolyte. Fig. 5 s ows a similar curve for the simultaneous electrodeposition of iron and nickel in accordance with the present invention.

In Fig. 1 of the drawings, the vat l0 contains an electrolyte 11 the anodes 12 and 13 and the cathode 14. 'Izhe battery l5 su plies a positive potential to the anodes whic ma be electricall connected, but means is pre erably provi ed for individually varying the potential applied to each anode so that the current flowing therethrough may be adjusted to a suitable value. The current owin through each anode is preferably so adjuste that a constant concentration of the ions of each metal vis maintained in the electrol e and the anode areas are preferably such t at the current per unit area is the same for each anode. When depositing a nickel-iron alloy composed of 79% nickel* and 21% iron, satisfactory results have been obtained by employin anodesphaving surface areas in the ratio o nickel to 15% iron. Instead of employing a plurality of anodes, one of each metal composing the alloy, a single anode composed of the alloy v and having suitable proportions of the component metals may be employed. In some cases it may be advantageous to employ anodes of one or more of the component metals of the alloy and a chemical compound, such as the hydroxide, of the remaining component metals. For instance, when depositing a nickel-iron alloy, a nickel'anode ma be em loyed and ferrous hydroxide may e adde to the electrolyte continuously or at regular intervals so as to maintain the concentration of the ferrous.

ions substantially constant.

The cathode 14: may be of any suitable composition and form, but where it is desired to stri the deposit from the cathode, it is prefera le to employ a flat cathode of a metal so treated that the deposited alloy does not adhere firmly to it.` When depositing nickel-v iron alloys, .satisfactory .results have been n a cathode ofbrass which has been treated either by dipping in selenic acid or by coating electrolytically in a solution of ammonium molybdate using the of uniform composition is metals remained constant.

ployed is a large slowly rotating cylinder K aving a portion of its surface submerged in the electrolyte. The deposited alloy is removed from the cathode as it leaves the electrolyte and a continuous strip of the alloy may thus be obtained;

Curve 20 of Fig. 2 shows the relation which exists between cathode potential and current density when nickel is deposited from an electrol te composed of niekelous sulphate and nic elous chloride, While curve 21 of the figure shows the relation when iron is deposited from an electrolyte of ferrous sulphate and ferrous chloride. In Fig. 3, curve 22 is a cathode potential-current density curve for the deposition of nickel from an electrolyte composed of nickelous sulphate, nickelous chloride and borc acid, while curve 23 of this ligure shows, on the same coordinates, the operating conditions for depositing iron from an electrolyte composed of ferrous` sulphate, ferrous chloride and boric acid. Curves 24 and 25 are obtained by employing electrolytes composed of the same ingredients as employed in obtaining curvesi22 and 23 respectively, of Fig. in each case of sodium sulphate. Curve 26 of Fig. 5 shows the conditions for depositing an alloy of nickel and iron from an electroy lyte having the combined ingredients used in lytes here used in obtaining the data shown plotted in Fig. 4, it is seen that curves for the two metals are made to practically coincide over a substantial portion of the current density range. For this condition a deposit obtained, when the metals are deposited simultaneously, since any change in current density will cause an equal change in the cathode potential for each of the lmetals composing the alloy and 'therefore an `equal change in the amount of each metal deposited.

In obtaining the curves of Fig. 5, the proportions of the constituents of the electrolyte were such that an alloy of approximatel 79% nickel and 21% iron was deposite The-size of the anodes and the spacing between the anodes and the cathode were' such that the concentration of the ions of both The electrolyte was maintained ata temperature of 50 C.

3, with the addition andthe average of the instantaneous values of current denslty was about 4 amperes per square decimeter. The ratio of the surfaces Vof the anodes was about 85% nickel to 15% liron and the currents iowing through the :modes were in about the same ratio. The amounts of the Various constituents of the electrolyte employed in depositing this alloy were as follows.:

Grams NiSOJHgO 212 FeSOl/THQO 22 NiCl2.6H2O 18 FeCl2.4H2O 1 2.5 HSBOS NagSO47IIgO ...Q

adhere firmly, or it may be one which perl mits the stripping of the deposited allo from the cathode. The invention is especia ly useful, however, in obtaining the deposited posited are substantially eratiig1 range of current densi an anode of nic e1a second anode of iron,

the ratio of the surface areas of the anodes nickel --and 15% being'approximately 85 iron, and a brass cathode which'hasj been treated by dipping in selenic acid,immersed in an electrolyte and means for -fappl 'ng a potential between said cathode Van said anodes, the composition of said electrolyte In witness whereof, I hereunto subscribe my name this 28th da of Au st, A: D. 1926.

ROBER M. B i, GLARENCE W. W' NER.

- 'alloy in the form of sheets which can be stripped from the cathode and which are thinner than can be conveniently obtainedby rolling. Sheets as thin as .0003 have been successfull made electrol ically. Even where a t icker sheet of a loy is required, it is found that rollin causes strains in the material which often give it undesirable elec--v trical or mechanical properties. The strains introduced when' emplo g the electrolytic method are of small or er and this method, therefore, may simplify the heat treatments of the alloy.-

What is claimed is:

1. In an apparatus for electrode ositing nickel-iron al oys, an anode of nicke a second anode of iron and a cathode immersed in an electrolyte composed ofnickelous sulphate, ferrous sulphate, nickelous chloride, ferrous chloride, sodium sulphate and boric acid, and means for applyln a potential between said cathode and sai anodes, the' proportions of said constituents of the elec-4 trolyte being adjusted so as to make the cathode potentials of the nickel and iron sub.- stantially equal over the operating portion of the. current density range.

2. In an apparatus for depositing an alloyA of approximately''(9% nickel and 21% iron, an anode of nickel, a second anode of iron, the surface areas ofthe anodes being apprxi mately nickelv and 15% iron, and a Acath-V ode immersed in an electrolyte andmeans for applying a potential -between saidcathode and said anodes, the composition of said elec- Y trclyte being 'such that the cathode potentials of the metals composing the alloy to be del equal over thel op.

an apparatus for deposi au allo l of approximatel 79% nickel and 1% irony, 

